有人尝试在 opencv 或 C++ 中实现 DWT 吗？ 我看到了关于这个主题的旧帖子，但我发现它们对我没有用，因为我需要近似系数和小波变换结果的细节。
我尝试将 this 添加到我的项目中，但它没有按计划运行。
这很简单，因为结果参数我需要近似系数和细节：
void haar1(float *vec, int n, int w)
{
int i=0;
float *vecp = new float[n];
for(i=0;i<n;i++)
vecp[i] = 0;
w/=2;
for(i=0;i<w;i++)
{
vecp[i] = (vec[2*i] + vec[2*i+1])/sqrt(2.0);
vecp[i+w] = (vec[2*i] - vec[2*i+1])/sqrt(2.0);
}
for(i=0;i<(w*2);i++)
vec[i] = vecp[i];
delete [] vecp;
}
void haar2(float **matrix, int rows, int cols)
{
float *temp_row = new float[cols];
float *temp_col = new float[rows];
int i=0,j=0;
int w = cols, h=rows;
while(w>1 || h>1)
{
if(w>1)
{
for(i=0;i<h;i++)
{
for(j=0;j<cols;j++)
temp_row[j] = matrix[i][j];
haar1(temp_row,cols,w);
for(j=0;j<cols;j++)
matrix[i][j] = temp_row[j];
}
}
if(h>1)
{
for(i=0;i<w;i++)
{
for(j=0;j<rows;j++)
temp_col[j] = matrix[j][i];
haar1(temp_col, rows, h);
for(j=0;j<rows;j++)
matrix[j][i] = temp_col[j];
}
}
if(w>1)
w/=2;
if(h>1)
h/=2;
}
delete [] temp_row;
delete [] temp_col;
}
那么有人可以帮我找到用 C++ 实现的 dwt 或告诉我如何从上面的代码系数中提取。谢谢
这是直接和逆 Haar 小波变换（用于滤波）：
#include "opencv2/opencv.hpp"
#include <iostream>
#include <vector>
#include <stdio.h>
using namespace cv;
using namespace std;
// Filter type
#define NONE 0 // no filter
#define HARD 1 // hard shrinkage
#define SOFT 2 // soft shrinkage
#define GARROT 3 // garrot filter
//--------------------------------
// signum
//--------------------------------
float sgn(float x)
{
float res=0;
if(x==0)
{
res=0;
}
if(x>0)
{
res=1;
}
if(x<0)
{
res=-1;
}
return res;
}
//--------------------------------
// Soft shrinkage
//--------------------------------
float soft_shrink(float d,float T)
{
float res;
if(fabs(d)>T)
{
res=sgn(d)*(fabs(d)-T);
}
else
{
res=0;
}
return res;
}
//--------------------------------
// Hard shrinkage
//--------------------------------
float hard_shrink(float d,float T)
{
float res;
if(fabs(d)>T)
{
res=d;
}
else
{
res=0;
}
return res;
}
//--------------------------------
// Garrot shrinkage
//--------------------------------
float Garrot_shrink(float d,float T)
{
float res;
if(fabs(d)>T)
{
res=d-((T*T)/d);
}
else
{
res=0;
}
return res;
}
//--------------------------------
// Wavelet transform
//--------------------------------
static void cvHaarWavelet(Mat &src,Mat &dst,int NIter)
{
float c,dh,dv,dd;
assert( src.type() == CV_32FC1 );
assert( dst.type() == CV_32FC1 );
int width = src.cols;
int height = src.rows;
for (int k=0;k<NIter;k++)
{
for (int y=0;y<(height>>(k+1));y++)
{
for (int x=0; x<(width>>(k+1));x++)
{
c=(src.at<float>(2*y,2*x)+src.at<float>(2*y,2*x+1)+src.at<float>(2*y+1,2*x)+src.at<float>(2*y+1,2*x+1))*0.5;
dst.at<float>(y,x)=c;
dh=(src.at<float>(2*y,2*x)+src.at<float>(2*y+1,2*x)-src.at<float>(2*y,2*x+1)-src.at<float>(2*y+1,2*x+1))*0.5;
dst.at<float>(y,x+(width>>(k+1)))=dh;
dv=(src.at<float>(2*y,2*x)+src.at<float>(2*y,2*x+1)-src.at<float>(2*y+1,2*x)-src.at<float>(2*y+1,2*x+1))*0.5;
dst.at<float>(y+(height>>(k+1)),x)=dv;
dd=(src.at<float>(2*y,2*x)-src.at<float>(2*y,2*x+1)-src.at<float>(2*y+1,2*x)+src.at<float>(2*y+1,2*x+1))*0.5;
dst.at<float>(y+(height>>(k+1)),x+(width>>(k+1)))=dd;
}
}
dst.copyTo(src);
}
}
//--------------------------------
//Inverse wavelet transform
//--------------------------------
static void cvInvHaarWavelet(Mat &src,Mat &dst,int NIter, int SHRINKAGE_TYPE=0, float SHRINKAGE_T=50)
{
float c,dh,dv,dd;
assert( src.type() == CV_32FC1 );
assert( dst.type() == CV_32FC1 );
int width = src.cols;
int height = src.rows;
//--------------------------------
// NIter - number of iterations
//--------------------------------
for (int k=NIter;k>0;k--)
{
for (int y=0;y<(height>>k);y++)
{
for (int x=0; x<(width>>k);x++)
{
c=src.at<float>(y,x);
dh=src.at<float>(y,x+(width>>k));
dv=src.at<float>(y+(height>>k),x);
dd=src.at<float>(y+(height>>k),x+(width>>k));
// (shrinkage)
switch(SHRINKAGE_TYPE)
{
case HARD:
dh=hard_shrink(dh,SHRINKAGE_T);
dv=hard_shrink(dv,SHRINKAGE_T);
dd=hard_shrink(dd,SHRINKAGE_T);
break;
case SOFT:
dh=soft_shrink(dh,SHRINKAGE_T);
dv=soft_shrink(dv,SHRINKAGE_T);
dd=soft_shrink(dd,SHRINKAGE_T);
break;
case GARROT:
dh=Garrot_shrink(dh,SHRINKAGE_T);
dv=Garrot_shrink(dv,SHRINKAGE_T);
dd=Garrot_shrink(dd,SHRINKAGE_T);
break;
}
//-------------------
dst.at<float>(y*2,x*2)=0.5*(c+dh+dv+dd);
dst.at<float>(y*2,x*2+1)=0.5*(c-dh+dv-dd);
dst.at<float>(y*2+1,x*2)=0.5*(c+dh-dv-dd);
dst.at<float>(y*2+1,x*2+1)=0.5*(c-dh-dv+dd);
}
}
Mat C=src(Rect(0,0,width>>(k-1),height>>(k-1)));
Mat D=dst(Rect(0,0,width>>(k-1),height>>(k-1)));
D.copyTo(C);
}
}
//--------------------------------
//
//--------------------------------
int process(VideoCapture& capture)
{
int n = 0;
const int NIter=4;
char filename[200];
string window_name = "video | q or esc to quit";
cout << "press space to save a picture. q or esc to quit" << endl;
namedWindow(window_name, CV_WINDOW_KEEPRATIO); //resizable window;
Mat frame;
capture >> frame;
Mat GrayFrame=Mat(frame.rows, frame.cols, CV_8UC1);
Mat Src=Mat(frame.rows, frame.cols, CV_32FC1);
Mat Dst=Mat(frame.rows, frame.cols, CV_32FC1);
Mat Temp=Mat(frame.rows, frame.cols, CV_32FC1);
Mat Filtered=Mat(frame.rows, frame.cols, CV_32FC1);
for (;;)
{
Dst=0;
capture >> frame;
if (frame.empty()) continue;
cvtColor(frame, GrayFrame, CV_BGR2GRAY);
GrayFrame.convertTo(Src,CV_32FC1);
cvHaarWavelet(Src,Dst,NIter);
Dst.copyTo(Temp);
cvInvHaarWavelet(Temp,Filtered,NIter,GARROT,30);
imshow(window_name, frame);
double M=0,m=0;
//----------------------------------------------------
// Normalization to 0-1 range (for visualization)
//----------------------------------------------------
minMaxLoc(Dst,&m,&M);
if((M-m)>0) {Dst=Dst*(1.0/(M-m))-m/(M-m);}
imshow("Coeff", Dst);
minMaxLoc(Filtered,&m,&M);
if((M-m)>0) {Filtered=Filtered*(1.0/(M-m))-m/(M-m);}
imshow("Filtered", Filtered);
char key = (char)waitKey(5);
switch (key)
{
case 'q':
case 'Q':
case 27: //escape key
return 0;
case ' ': //Save an image
sprintf(filename,"filename%.3d.jpg",n++);
imwrite(filename,frame);
cout << "Saved " << filename << endl;
break;
default:
break;
}
}
return 0;
}
int main(int ac, char** av)
{
VideoCapture capture(0);
if (!capture.isOpened())
{
return 1;
}
return process(capture);
}
这里是 OpenCV 中小波变换的另一种实现，来自 Mahavir：
#include <opencv2\highgui\highgui.hpp>
#include <opencv2\core\core.hpp>
#include <opencv2\core\mat.hpp>
#include <opencv2\imgproc\imgproc.hpp>
#include<iostream>
#include<math.h>
#include<conio.h>
using namespace std;
using namespace cv;
class image
{
public:
Mat im,im1,im2,im3,im4,im5,im6,temp,im11,im12,im13,im14,imi,imd,imr;
float a,b,c,d;
int getim();
};
int image::getim()
{
im=imread("lena.jpg",0); //Load image in Gray Scale
imi=Mat::zeros(im.rows,im.cols,CV_8U);
im.copyTo(imi);
im.convertTo(im,CV_32F,1.0,0.0);
im1=Mat::zeros(im.rows/2,im.cols,CV_32F);
im2=Mat::zeros(im.rows/2,im.cols,CV_32F);
im3=Mat::zeros(im.rows/2,im.cols/2,CV_32F);
im4=Mat::zeros(im.rows/2,im.cols/2,CV_32F);
im5=Mat::zeros(im.rows/2,im.cols/2,CV_32F);
im6=Mat::zeros(im.rows/2,im.cols/2,CV_32F);
//--------------Decomposition-------------------
for(int rcnt=0;rcnt<im.rows;rcnt+=2)
{
for(int ccnt=0;ccnt<im.cols;ccnt++)
{
a=im.at<float>(rcnt,ccnt);
b=im.at<float>(rcnt+1,ccnt);
c=(a+b)*0.707;
d=(a-b)*0.707;
int _rcnt=rcnt/2;
im1.at<float>(_rcnt,ccnt)=c;
im2.at<float>(_rcnt,ccnt)=d;
}
}
for(int rcnt=0;rcnt<im.rows/2;rcnt++)
{
for(int ccnt=0;ccnt<im.cols;ccnt+=2)
{
a=im1.at<float>(rcnt,ccnt);
b=im1.at<float>(rcnt,ccnt+1);
c=(a+b)*0.707;
d=(a-b)*0.707;
int _ccnt=ccnt/2;
im3.at<float>(rcnt,_ccnt)=c;
im4.at<float>(rcnt,_ccnt)=d;
}
}
for(int rcnt=0;rcnt<im.rows/2;rcnt++)
{
for(int ccnt=0;ccnt<im.cols;ccnt+=2)
{
a=im2.at<float>(rcnt,ccnt);
b=im2.at<float>(rcnt,ccnt+1);
c=(a+b)*0.707;
d=(a-b)*0.707;
int _ccnt=ccnt/2;
im5.at<float>(rcnt,_ccnt)=c;
im6.at<float>(rcnt,_ccnt)=d;
}
}
imr=Mat::zeros(256,256,CV_32F);
imd=Mat::zeros(256,256,CV_32F);
im3.copyTo(imd(Rect(0,0,128,128)));
im4.copyTo(imd(Rect(0,127,128,128)));
im5.copyTo(imd(Rect(127,0,128,128)));
im6.copyTo(imd(Rect(127,127,128,128)));
//---------------------------------Reconstruction-------------------------------------
im11=Mat::zeros(im.rows/2,im.cols,CV_32F);
im12=Mat::zeros(im.rows/2,im.cols,CV_32F);
im13=Mat::zeros(im.rows/2,im.cols,CV_32F);
im14=Mat::zeros(im.rows/2,im.cols,CV_32F);
for(int rcnt=0;rcnt<im.rows/2;rcnt++)
{
for(int ccnt=0;ccnt<im.cols/2;ccnt++)
{
int _ccnt=ccnt*2;
im11.at<float>(rcnt,_ccnt)=im3.at<float>(rcnt,ccnt); //Upsampling of stage I
im12.at<float>(rcnt,_ccnt)=im4.at<float>(rcnt,ccnt);
im13.at<float>(rcnt,_ccnt)=im5.at<float>(rcnt,ccnt);
im14.at<float>(rcnt,_ccnt)=im6.at<float>(rcnt,ccnt);
}
}
for(int rcnt=0;rcnt<im.rows/2;rcnt++)
{
for(int ccnt=0;ccnt<im.cols;ccnt+=2)
{
a=im11.at<float>(rcnt,ccnt);
b=im12.at<float>(rcnt,ccnt);
c=(a+b)*0.707;
im11.at<float>(rcnt,ccnt)=c;
d=(a-b)*0.707; //Filtering at Stage I
im11.at<float>(rcnt,ccnt+1)=d;
a=im13.at<float>(rcnt,ccnt);
b=im14.at<float>(rcnt,ccnt);
c=(a+b)*0.707;
im13.at<float>(rcnt,ccnt)=c;
d=(a-b)*0.707;
im13.at<float>(rcnt,ccnt+1)=d;
}
}
temp=Mat::zeros(im.rows,im.cols,CV_32F);
for(int rcnt=0;rcnt<im.rows/2;rcnt++)
{
for(int ccnt=0;ccnt<im.cols;ccnt++)
{
int _rcnt=rcnt*2;
imr.at<float>(_rcnt,ccnt)=im11.at<float>(rcnt,ccnt); //Upsampling at stage II
temp.at<float>(_rcnt,ccnt)=im13.at<float>(rcnt,ccnt);
}
}
for(int rcnt=0;rcnt<im.rows;rcnt+=2)
{
for(int ccnt=0;ccnt<im.cols;ccnt++)
{
a=imr.at<float>(rcnt,ccnt);
b=temp.at<float>(rcnt,ccnt);
c=(a+b)*0.707;
imr.at<float>(rcnt,ccnt)=c; //Filtering at Stage II
d=(a-b)*0.707;
imr.at<float>(rcnt+1,ccnt)=d;
}
}
imd.convertTo(imd,CV_8U);
namedWindow("Input Image",1);
imshow("Input Image",imi);
namedWindow("Wavelet Decomposition",1);
imshow("Wavelet Decomposition",imd);
imr.convertTo(imr,CV_8U);
namedWindow("Wavelet Reconstruction",1);
imshow("Wavelet Reconstruction",imr);
waitKey(0);
return 0;
}
int main()
{
image my;
my.getim();
return 0;
}
希望有人觉得它有用！
我发现 java 中小波的代码示例非常少，特别是如果您使用 openCV。我必须在 java 中使用小波和 openCV，我使用了 @la luvia 的 C 代码并转换为 java。
翻译代码的时候遇到了很多麻烦，因为它与openCV的方法和使用方式有很多差异。这本书在这个过程中也给了我很大帮助。
我希望这段代码和本书能够提供一些如何使用该库的视角以及 C 和 Java 之间的一些差异。
这是代码：
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
public class Wavelet {
//Imperative in java
static{
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
}
String pathname = "C:/Users/user/img096";
public static void main(String[] args) {
Wavelet wavelet = new Wavelet();
wavelet.applyHaarFoward();
wavelet.applyHaarReverse();
Imgcodecs.imwrite(wavelet.pathname+"imi.jpg", wavelet.imi);
Imgcodecs.imwrite(wavelet.pathname+"imd.jpg", wavelet.imd);
Imgcodecs.imwrite(wavelet.pathname+"imr.jpg", wavelet.imr);
}
Mat im,im1,im2,im3,im4,im5,im6,temp,im11,im12,im13,im14,imi,imd,imr;
float a,b,c,d;
private void applyHaarFoward(){
try{
im = Imgcodecs.imread(pathname+".jpg", 0);
imi = new Mat(im.rows(), im.cols(), CvType.CV_8U);
im.copyTo(imi);
//in CvType. If the number of channels is omitted, it evaluates to 1.
im.convertTo(im, CvType.CV_32F, 1.0, 0.0);
im1 = new Mat(im.rows()/2, im.cols(), CvType.CV_32F);
im2 = new Mat(im.rows()/2, im.cols(), CvType.CV_32F);
im3 = new Mat(im.rows()/2, im.cols()/2, CvType.CV_32F);
im4 = new Mat(im.rows()/2, im.cols()/2, CvType.CV_32F);
im5 = new Mat(im.rows()/2, im.cols()/2, CvType.CV_32F);
im6 = new Mat(im.rows()/2, im.cols()/2, CvType.CV_32F);
// ------------------- Decomposition -------------------
for (int rcnt = 0; rcnt < im.rows(); rcnt+=2) {
for (int ccnt = 0; ccnt < im.cols(); ccnt++) {
//even though the CvType is float with only one channel
//the method Mat.get() return a double array
//with only one position, [0].
a = (float) im.get(rcnt, ccnt)[0];
b = (float) im.get(rcnt+1, ccnt)[0];
c = (float) ((a+b)*0.707);
d = (float) ((a-b)*0.707);
int _rcnt= rcnt/2;
im1.put(_rcnt, ccnt, c);
im2.put(_rcnt, ccnt, d);
}
}
for (int rcnt = 0; rcnt < im.rows()/2; rcnt++) {
for (int ccnt = 0; ccnt < im.cols() - 2; ccnt+=2) {
a = (float) im1.get(rcnt, ccnt)[0];
b = (float) im1.get(rcnt, ccnt+1)[0];
c = (float) ((a+b)*0.707);
d = (float) ((a-b)*0.707);
int _ccnt = ccnt/2;
im3.put(rcnt, _ccnt, c);
im4.put(rcnt, _ccnt, d);
}
}
for (int rcnt = 0; rcnt < im.rows()/2; rcnt++) {
for (int ccnt = 0; ccnt < im.cols() - 2; ccnt+=2) {
a = (float) im2.get(rcnt, ccnt)[0];
b = (float) im2.get(rcnt, ccnt+1)[0];
c = (float) ((a+b)*0.707);
d = (float) ((a-b)*0.707);
int _ccnt = ccnt/2;
im5.put(rcnt, _ccnt, c);
im6.put(rcnt, _ccnt, d);
}
}
imr = Mat.zeros(im.rows(), im.cols(), CvType.CV_32F);//imr = Mat.zeros(512, 512, CvType.CV_32F);
imd = Mat.zeros(512, 512, CvType.CV_32F);
im3.copyTo(imd.adjustROI(0, 0, 256, 256));
im4.copyTo(imd.adjustROI(0, 255, 256, 256));
im5.copyTo(imd.adjustROI(255, 0, 256, 256));
im6.copyTo(imd.adjustROI(255, 255, 256, 256));
}catch(Exception ex){
System.err.println(ex.getLocalizedMessage());
ex.printStackTrace();
}
}
private void applyHaarReverse(){
// ------------------- Reconstruction -------------------
im11 = Mat.zeros(im.rows()/2, im.cols(), CvType.CV_32F);
im12 = Mat.zeros(im.rows()/2, im.cols(), CvType.CV_32F);
im13 = Mat.zeros(im.rows()/2, im.cols(), CvType.CV_32F);
im14 = Mat.zeros(im.rows()/2, im.cols(), CvType.CV_32F);
for (int rcnt = 0; rcnt < im.rows()/2; rcnt++) {
for (int ccnt = 0; ccnt < im.cols()/2; ccnt++) {
int _ccnt = ccnt*2;
im11.put(rcnt, _ccnt, im3.get(rcnt, ccnt));
im12.put(rcnt, _ccnt, im4.get(rcnt, ccnt));
im13.put(rcnt, _ccnt, im5.get(rcnt, ccnt));
im14.put(rcnt, _ccnt, im6.get(rcnt, ccnt));
}
}
for (int rcnt = 0; rcnt < im.rows()/2; rcnt++) {
for (int ccnt = 0; ccnt < im.cols() - 2; ccnt+=2) {
a = (float) im11.get(rcnt, ccnt)[0];
b = (float) im12.get(rcnt, ccnt)[0];
c = (float) ((a+b)*0.707);
im11.put(rcnt, ccnt, c);
d = (float) ((a-b)*0.707);
im11.put(rcnt, ccnt+1, d);
a = (float) im13.get(rcnt, ccnt)[0];
b = (float) im14.get(rcnt, ccnt)[0];
c = (float) ((a+b)*0.707);
im13.put(rcnt, ccnt, c);
d = (float) ((a-b)*0.707);
im13.put(rcnt, ccnt+1, d);
}
}
temp = Mat.zeros(im.rows(), im.cols(), CvType.CV_32F);
for (int rcnt = 0; rcnt < im.rows()/2; rcnt++) {
for (int ccnt = 0; ccnt < im.cols(); ccnt++) {
int _rcnt = rcnt*2;
imr.put(_rcnt, ccnt, im11.get(rcnt, ccnt));
temp.put(_rcnt, ccnt, im13.get(rcnt, ccnt));
}
}
for (int rcnt = 0; rcnt < im.rows()-2; rcnt+=2) {
for (int ccnt = 0; ccnt < im.cols(); ccnt++) {
a = (float) imr.get(rcnt, ccnt)[0];
b = (float) temp.get(rcnt, ccnt)[0];
c = (float) ((a+b)*0.707);
imr.put(rcnt, ccnt, c);
d = (float) ((a-b)*0.707);
imr.put(rcnt+1, ccnt, d);
}
}
}
}
希望有用。
建议： 我不建议你从头开始实现dwt，很难满足你的要求。 如果你的工作中确实需要它的cpp版本，我建议你尝试PyWavelets，它的dwt基本功能是用C实现的，因此你可以轻松地将其迁移到你的程序中。 否则，你也可以先用python验证一下你的想法，而不是冒着付出无用功的风险。
如果你想改变小波滤波器，你可以使用matlab（
wfilters(wname)